Introduction
This section will focus on some popular circuit simulators both and
will include some tutorials.

Until computers were available, circuit analysis was done by hand
with pencil and paper, calculations were long and often prone to error.
With a computer, results are available in seconds and printouts can be
produced. Also, measurements which would be difficult or impossible to
do on a real circuit can be made on a simulator. Many programs allow
schematic capture and some even allow creation of a PCB layout. You
still have to design the circuit yourself, and results will only be as
good as your initial circuit input.

Most Simulation programs are based on the original 1970's
SPICE
program and some have additional features. The original Spice2 program was wrote in fortran and contained models for transistors, FET's,
diodes, resistors and capacitors and could perform AC and DC analysis, transient and time domain analysis. The later Spice3 version included
models for MOSFET and added noise, distortion and pole-zero analysis, temperature sweeping, monte carlo and fourier analysis.

Though not a simulator itself, Kicad is a very capable PCB drafting program and will also be featured in this
section. Click the logos for the appropriate simulator page.

Click the logos for the appropriate simulator page.

"TINA" stands for (Toolkit for Interactive
Network Analysis) and is made by from designsoft. It has schematic capture and can perform many analog and digital analyses.

LT Spice IV is a free spice 3 based simulator from Linear Technology.
Originally called Switchercad this simulator was used in analyzing
switched mode power supplies, but has the ability to work with
transistors, FET's and IC's and has become an invaluable tool for
circuit simulation and schematic drafting. To get a copy, visit this
page on Linear Technologies web site. The program can be run under both windows and linux.

Sadly Circuit Maker is no longer available but has now become Altium Designer.
Circuit Maker was the first program I ever bought and there's still a
large following and I hope you find something useful in this section.

Kicad though
not a simulator in itself, is an open source schematic capture and PCB
drafting program. Designed and written by Jean-Pierre Charras,
it runs on both windows and linux and features auto and manual,
routing, output in gerber format and can generate beautiful rendered 3D
graphics view of your PCB.